JavaScript Minifier

What is the JavaScript Minifier?

JavaScript is usually the heaviest part of a web page, and every kilobyte has to be downloaded, parsed and executed. Minification shrinks scripts by removing comments, whitespace and line breaks, and in more advanced tools by renaming local variables to short names and simplifying expressions.

A simple minifier like this one focuses on safe, whitespace and comment removal. That is predictable and will not break your code, but it saves less than a full optimizer such as Terser or esbuild, which also shorten identifiers. For production, use a build tool with source maps; use this page for snippets, bookmarklets and quick checks.

When to use the JavaScript Minifier

It suits small scripts that do not go through a bundler: analytics snippets, bookmarklets saved in the browser, inline scripts for static pages, and code you paste into a CMS field with a length limit. Smaller scripts download and parse faster, which improves interactivity on slow connections. The beautify mode helps when you need to read a vendor script or investigate a production error that points to line 1, column 48210 of a minified bundle.

How to use the JavaScript Minifier

1. Paste your JavaScript into the input area.
2. Choose Minify or Beautify.
3. Review the output and the reported size reduction.
4. Copy the result into your page, bookmarklet or build output.
5. Run your code once in the browser console to confirm it still works.

Examples

Source:

// Add two numbers
function add(a, b) {
  const sum = a + b;
  return sum;
}
console.log(add(2, 3));

Minified (whitespace and comments removed):

function add(a,b){const sum=a+b;return sum}console.log(add(2,3));

Common errors and tips

• Missing semicolons relying on automatic semicolon insertion can break when lines are joined; terminate statements explicitly.
• A // comment at the end of a line must be removed before joining lines, or it would comment out the following code.
• Regular expressions and template literals contain whitespace that is significant and must not be altered.
• Never rely on function names (fn.name) in code that will be renamed by an advanced minifier.
• Always keep the unminified source and a source map for debugging production errors.

Privacy: runs entirely in your browser

Your source code is processed entirely in the browser; proprietary scripts are never uploaded or stored. This tool runs entirely in your browser: nothing you enter is uploaded, stored or logged on our servers, and it keeps working even if you go offline after the page has loaded.